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help for ^parcoord^						(STB-29: gr18)
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graph multivariate data in parallel coordinates
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   ^parcoord^ varlist [^if^ exp] [^in^ range] 
             [^,^ ^by(^byvar^)^ ^cen^ter ^col^orby^(^idvar^)^ ^e^cho ^tour^ graph_options] 


Description
-----------

^parcoord^ draws a parallel coordinates plot for the variables in varlist.  A
parallel coordinates plot provides an alternative to the scatterplot matrix for
visually examining many variables simultaneously. Variables in varlist are rep-
resented as parallel vertical axes; each observation is plotted as a collection
of line segments joined end-to-end.  Subsets of observations can be selected
with ^if^ and ^in^ clauses; an observation will be ignored if it has missing val-
ues for any of the byvar, idvar, or varlist variables.


Options
-------

^by(byvar)^ uses the ^by^ option of the ^graph^ command to draw a separate plot for
    each value of byvar.  The graph option ^total^ may be used with this option.

^center^ scales each axis so that the median of the corresponding variable falls
    at the midpoint and all data fall within the length of the axis.  The de-
    fault is to scale each axis to extend from the minimum to the maximum value
    of the variable represented.

^colorby(idvar)^ assigns different pens to observations with different values of
    idvar.  On color monitors, this displays subsets of observations (defined
    by idvar) in different colors.

^echo^ prints the names of the axes (variables), in left-right order, to the Re-
    sults screen before drawing the plot.  (Useful if the number of variables
    is large and the variable names are hard to read in the plot.)

^tour^ generates a sequence of plots by repeatedly permuting the left-right order
    of the variables in the plot.  By default, axes are drawn in the same order
    that the variables appear in the varlist.  ^tour^ permutes the axes such that
    each possible pair of the p variables in varlist is represented on adjacent
    axes within the first (p+1)/2 plots of the tour. The tour pauses after each
    plot and displays ^--more--^.  The tour continues endlessly, until the user
    presses the ^Break^ key, although the tour is largely redundant after the
    first (p+1)/2 plots.

graph_options are any of the options allowed with graph, twoway, except for:
    by, b2title, connect, noaxis, pen, symbol, tlabel, xlabel, xline, ylabel,
    yline.


Examples
--------

 . ^parcoord ftime*, center^
   (plot all variables whose names begin with ftime. Variables assigned to axes
   in the same order that they appear in the data set; axes scaled so that the
   median of each ftime variable is at the axis midpoint.)

 . ^parcoord xa1 xa2 yb1 yb2 yb3 yb4 if time > 50, col(trt)^
   (one 6-dimensional parallel coordinates plot for all cases where time > 50;
   observations at different values of trt drawn in different colors.)

 . ^parcoord bwt1-bwt12 if !censor, by(site) tour echo^
   (sequence of graphs for cases where censor == 0; each graph contains a par-
   allel coordinates plot for each value of site.  Successive graphs alter the
   left-right order of the variables bwt1-bwt12 within each plot; that ordering
   is printed to the Results screen before each graph is drawn.)


Author
------
	John R. Gleason
        Syracuse University
	73241.717@@compuserve.com


Also see
-------- 

    STB:  STB-29 gr18
 Manual:  [3] by, [3] matrix, [3] pens
On-line:  help for @graph@, @scatterplot@